Perhaps the most testing challenge that confronts crime drama is how to stay the right side of absurdity. It doesn't matter how good the acting is, or how impressive the location work, a sinking feeling will inevitably set in if the plot is ludicrously unrealistic. So Wallander, for example, may be bathed in naturalism, but it's also bathed in blood, and therefore in the Swedish countryside, where murderers are as rare as coconut palms, belief is the preserve of the credulous.

Happily, there is a place in which a great deal of tireless work – grazie Silvio Berlusconi – has been done to redraft the borders of absurdity, and its name is Italy. It's the ideal environment for crime drama because there's no need to waste valuable time on creating a backstory of corruption and intrigue. Like shady piazzas and crumbling palazzos, it comes with the terrain.

Say what you like, though, about the moral imperfections of the Italian criminal justice system, it does not tolerate physical imperfection. Even with its washed-out, gritty colour, everything and everyone looked exquisitely beautiful in Zen, a lavish new detective series based on Michael Dibdin's novels and set in Rome.

There was not a Taggart or a Lewis in sight. Instead, there was the demon-eyed Rufus Sewell in a suit so watchable it deserved a separate acting credit. Sewell is a versatile performer whose intelligence probably hasn't been given the recognition it deserves. But then it's hard enough to forgive him his physiognomic good fortune without having to add praise on top.

He played Aurelio Zen, a wry cop who is separated from his wife and living with his mother. Zen is possessed of a unique reputation for incorruptibility, though he's not above playing the system if opportunity arises. In the first of three films, he wooed his boss's married secretary (Caterina Murino) with such ingenious passivity that she had to ask if they were going to have an affair. He was also sexually propositioned by a criminal witness, trapped in a flooded cave, twice faced execution, and throughout appeared less ruffled than a man visiting a new barber.

Alongside Sewell, crammed razored cheek by lantern jaw, was a gallery of British male – how to put it? – talent: Greg Wise, Ed Stoppard, Ben Miles and a rare TV sighting of Anthony Higgins. If they all looked as though they'd stepped out of the pages of L'Uomo Vogue, they sounded as though they'd just flown in from Stansted.

Like its stablemate, 'Wallander', 'Zen' relies on the jarring conceit of sticking a cast of British actors in a foreign setting to play foreigners with British accents. Strangely, it works, perhaps because it's so visually arresting that the ear soon gives up without much protest.

Or at least it works with the men. With the women, it's a different question, because by and large they are Italian. Andy Harries, who runs the company (Left Bank Pictures) that produced 'Zen' (and 'Wallander'), has said that British actresses can't play Italian women because there's something distinctive about the Italian female "form".

It's one of those arguments to which one could raise all manner of intellectual and ideological objections, but the truth is I couldn't remember what any of them were when Murino arrived on screen.

She is not the type of civilian assistant you might occasionally glimpse in 'The Bill' or, come to that, down at your local nick. If I say that Murino was previously best known for playing a Bond girl in 'Casino Royale', that conveys some idea of her "form", but not nearly enough. Put it this way, she made Sewell look plain. She made him look English.

With all that distracting surface to boast, 'Zen' could easily have been an empty vessel underneath. That it wasn't was due to some temperately judged performances – neither too hot nor too cool – a crisp script, a couple of enjoyable set pieces and a labyrinthine storyline that, thanks to its setting, just managed to stay the right side of absurd.